Screw propeller



FIG. 1 is a top, front perspective view of a screw propeller showing ourinvention;

FIG. 2 is a bottom, front perspective view of the screw propeller ofFIG. 1;

FIG. 3 is a front view of the screw propeller of FIG. 1;

FIG. 4 is a rear view of the screw propeller of FIG. 1;

FIG. 5 is an enlarged right side view of the screw propeller of FIG. 1;

FIG. 6 is a left side view of the screw propeller of FIG. 1;

FIG. 7 is a greatly enlarged top view of the screw propeller of FIG. 1;and,

FIG. 8 is a greatly enlarged bottom view of the screw propeller of FIG.1;

We claim the ornamental design for a screw propeller, as shown anddescribed.